UFC 3-270-02
15 March 2001
place of a router if the blade has a diameter of 6 inches (150 millimeters) or less (Figure 6.4.).
The 6-inch- (150-millimeter-) diameter blade allows the saw to follow slightly meandering cracks;
however, a saw blade does not follow the meandering crack as well as a router. If a saw is used
to widen the crack, a high-pressure water stream can be used to remove the debris created by
the saw (Figure 6.5.).
6.3.3. Hot compressed-air (HCA) heat lance. The HCA heat lance (Figure 6.6.) is used to warm,
dry, and clean the crack when the sealing operation must be conducted in less than desirable
conditions. Such conditions occur following rain or when the pavement temperature is below
50 degrees Fahrenheit (10 degrees Celsius). The heat lance can also be used to remove small
amounts of vegetation from cracks. Heat lances are capable of producing heated air at
3,000 degrees Fahrenheit (1,650 degrees Celsius) at velocities of up to 3,000 feet per second
(915 meters per second); therefore, extreme care must be used by the operator. The heat lance
should not remain stationary over one spot but should be kept moving to ensure that the asphalt
pavement is not overheated. Overheating will cause the pavement to become charred and brittle,
resulting in premature sealant bond failure. Heating the cracks using direct flame methods
should not be permitted. Direct flames harden the asphalt and leave a sooty residue that
prevents adequate bonding of the sealant to the asphalt pavement.
6.3.4. Sandblasting equipment. Sandblasting equipment (Figure 6.7.) is used to remove residue
left by the saw, loosened aggregate left by the router, vegetation, and other debris. If debris is
left in the crack, the sealant will not bond adequately to the asphalt, causing premature failure.
Equipment for sandblasting consists of an air compressor, hoses, and a venturi-type nozzle with
an opening not to exceed 1/4 inch (6 millimeters). The air compressor should be equipped with
traps that will keep the compressed air free of oil and moisture. The compressor should be
capable of supplying air at 150 cubic feet per second (4 cubic meters per second) and
maintaining a line pressure of 90 pounds per square inch (620 kilopascals). Caution should be
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